Sheet post-processing apparatus and method for controlling the sheet post-processing apparatus

ABSTRACT

According to embodiments, a sheet post-processing apparatus includes a processing tray, a vertical alignment section, a horizontal alignment section and a controller. The controller is configured to control the horizontal alignment section to shift the sheet to a first alignment position a predetermined distance from the center of the processing tray in the sheet width direction, control the horizontal alignment section to align the sheet in the sheet width direction at the first alignment position, and control the vertical alignment section to align the sheet in the conveying direction at the first alignment position, control the horizontal alignment section to realign the sheet at the first alignment position.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/385,852, filed on Dec. 20, 2016, which claims priority from JapanesePatent Application No. 2016-092039, filed on Apr. 28, 2016, the entirecontents of each of which are incorporated herein by reference.

FIELD

Embodiments described herein generally relate to a sheet post-processingapparatus.

BACKGROUND

A sheet post-processing apparatus is known which executes apost-processing such as a stapling processing on sheets loaded on aprocessing tray. In order to adjust deviation between the sheets loadedon the processing tray which are subjected to the post-processing, thesheet post-processing apparatus includes a horizontal aligning memberand a vertically aligning member. The horizontal aligning member is amember for aligning a deviation in the width direction of the sheet. Thevertical aligning member is a member for aligning a deviation in adirection orthogonal to the width direction of the sheet.

The above vertical aligning member is fixed against the sheetpost-processing apparatus. Thus, the aligning processing by verticalaligning member might cause the deviation of sheets to arise, dependingon the position of sheet aligning.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating an image forming system according to anembodiment.

FIG. 2 is an electrical block diagram illustrating an image formingapparatus and a sheet post-processing apparatus.

FIG. 3 is a diagram illustrating details of the configuration of eachsection of the sheet post-processing apparatus.

FIG. 4 is a diagram illustrating a relation between a standby tray, aprocessing tray and a paddle section.

FIG. 5 is top view illustrating a relation between the paddle sectionand the processing tray.

FIGS. 6-8 illustrate an action of the paddle.

FIG. 9 illustrates a control performed by a processor.

FIGS. 10-18 illustrate an action on the sheets loaded on the processingtray.

FIG. 19 illustrates a phenomenon of sheet deviation which is occurred byperforming a vertical alignment processing at a first alignmentposition.

FIGS. 20-22 illustrate the processing for the sheets on the processingtray performed by the horizontal alignment member and the paddle.

FIG. 23 is a flowchart illustrating the processing performed by thecontroller according to a second embodiment

FIG. 24 is a flowchart illustrating the processing performed by thecontroller according to a third embodiment.

DETAILED DESCRIPTION

According to an embodiment, a sheet post processing apparatus includes aprocessing tray, a vertical alignment section, a horizontal alignmentsection and a controller. The processing tray loads a sheet. Thevertical alignment section that is attached to a rotational shaft,aligns the sheet on the processing tray in a sheet conveying directionby rotating around the rotational shaft. The horizontal alignmentsection is configured to align the sheet in a sheet width directionorthogonal to the sheet conveying direction, by sandwiching with a firstalignment member and a second alignment member. The controller controlsthe horizontal alignment section to shift the sheet to a first alignmentposition a predetermined distance from the center of the processing trayin the sheet width direction, controls the horizontal alignment sectionto align the sheet in the sheet width direction at the first alignmentposition, and controls the vertical alignment section to align the sheetin the conveying direction at the first alignment position, controls thehorizontal alignment section to realign the sheet at the first alignmentposition.

Hereinafter, the sheet post-processing apparatus of the embodiment isdescribed with reference to the accompanying drawings. Furthermore, inthe following description, the same numerals are applied toconfigurations having identical or similar functions. Further, there isa case in which the repeated description of these configurations isomitted.

FIG. 1 is a diagram illustrating the entire configuration of an imageforming system. FIG. 2 is an electrical block diagram illustrating animage forming apparatus and a sheet post-processing apparatus. The imageforming system includes an image forming apparatus 1 and a sheetpost-processing apparatus 2. The image forming apparatus 1 forms animage on a sheet-like medium (hereinafter, referred to as a “sheet”)such as a paper. The sheet post-processing apparatus 2 carries out apost processing on a sheet conveyed from the image forming apparatus 1.

The image forming apparatus 1 includes a control panel 11, a scannersection 12, a printer section 13, a sheet feed section 14, a sheetdischarge section 15, an controller 16 and a communication interface 17.

The control panel 11 has interface including various keys for receivingoperations of a user. For example, the control panel 11 receives aninput relating to a type of the post processing of the sheet. Thecontrol panel 11 sends information relating to the input type of thepost processing to the sheet post-processing apparatus 2.

The scanner section 12 includes a reading section for reading imageinformation of a scanning target. The scanner section 12 sends the readimage information to the printer section 13.

The printer section 13 forms an image (hereinafter, referred to as a“toner image”) with a developing agent such as toner on the basis of theimage information sent from the scanner section 12 or an external devicesuch as a client PC. The printer section 13 transfers the toner imageonto a surface of the sheet. The printer section 13 fixes the tonerimage by applying heat and pressure to the toner image transferred ontothe sheet.

The sheet feed section 14 supplies the sheets one by one to the printersection 13. The sheet discharge section 15 conveys the sheet from theprinter section 13 to the sheet post-processing apparatus 2.

As shown in FIG. 2, the controller 16 controls all operations of theimage forming apparatus 1. In other words, the controller 16 controlsthe control panel 11, the scanner section 12, the printer section 13,the sheet feed section 14 and the sheet discharge section 15. Thecontroller 16 is formed by a control circuit including a CPU, a ROM anda RAM that are not shown. Further, the communication interface 17 sendsthe information relating to a printing job that is send from the controlpanel 11 and the external device to the sheet post-processing apparatus2.

Next, the configuration of the sheet post-processing apparatus 2 isdescribed with reference to FIG. 1 and FIG. 2. As shown in FIG. 1, thesheet post-processing apparatus 2 is arranged adjacent to the imageforming apparatus 1. The sheet post-processing apparatus 2 executes apost processing on the sheet conveyed from the image forming apparatus1. The post processing executed by the sheet post-processing apparatus 2is designated through the control panel 11 or the external device suchas a client PC. For example, the post processing includes a staplingprocessing or a sorting processing.

The sheet post-processing apparatus 2 includes a standby section 21, aprocessing section 22, a discharge section 23, a controller 24 and acommunication interface 40. The standby section 21 temporarily buffers asheet S (refer to FIG. 3) conveyed from the image forming apparatus 1.For example, the standby section 21 enables a plurality of followingsheets S to stand by while the post processing on the preceding sheetsis carried out by the processing section 22. The standby section 21 isarranged above the processing section 22. The standby section 21 enablesthe buffered plurality of sheets to drop towards the processing section22 if the sheet in the processing section 22 is discharged to thedischarge section 23.

The processing section 22 carries out the post processing on the sheetS. For example, the processing section 22 carries out the staplingprocessing on a plurality of the aligned sheets S. In this way, aplurality of the sheets is bound together by the staple. The processingsection 22 discharges the sheet S on which the post processing iscarried out to the discharge section 23.

The discharge section 23 includes a fixed tray 23 a and a movable tray23 b. The fixed tray 23 a is arranged on the upper part of the sheetpost-processing apparatus 2. The movable tray 23 b is arranged on theside of the sheet post-processing apparatus 2. The sheet S to which thestapling processing or the sorting processing is carried out isdischarged to the movable tray 23 b. The movable tray 23 b receives thesheet S which is stapled or sorted.

As shown in FIG. 2, the controller 24 controls all operations of thesheet post-processing apparatus 2. The controller 24 controls thestandby section 21, the processing section 22 and the discharge section23. Further, the controller 24 controls an inlet roller 32 a, an exitroller 33 a, a paddle section 25, a paddle motor 28, a first horizontalalignment motor 29 a, a second horizontal alignment motor 29 b, a firstalignment member 51 a and a second alignment member 51 b. The controller24 includes a control circuit containing a CPU 241, a ROM 242 and a RAM243. The first horizontal alignment member 51 a and the secondhorizontal alignment 51 b may be configured to be movable by one motor.The communication interface 40 receives the information such as aprinting job sent from the image forming apparatus 2. Further thecommunication interface 40 sends an error information regardingoccurring in the sheet post-processing apparatus 2.

FIG. 3 illustrates a configuration of the sheet post-processingapparatus 2. Furthermore, a “sheet conveyance direction” described inthe present embodiment refers to a conveyance direction D of the sheet Sto the standby tray 211 of the standby section 21 (an approach directionof the sheet S to the standby tray 211) or a direction in which thesheet S is conveyed from the processing tray 221 to the movable tray 23b. Further, an “upstream side” and a “downstream side” described in thepresent embodiment respectively refer to the upstream side and thedownstream side in the sheet conveyance direction D. Further, a “frontend part” and a “back end part” described in the present embodimentrespectively refer to “the end part of the downstream side” and “the endpart of the upstream side” in the sheet conveyance direction D. In thepresent embodiment, a direction orthogonal to the sheet conveyancedirection D is referred to as a sheet width direction W.

A conveyance path 31 is a conveyance path from a sheet supply port 31 pto a sheet discharge port 31 d. The sheet supply port 31 p is arrangedat a position facing the image forming apparatus 1. The sheet S issupplied from the image forming apparatus 1 to the sheet supply port 31p. On the other hand, the sheet discharge port 31 d is located in thevicinity of the standby section 21. The sheet S discharged from theimage forming apparatus 1 is discharged to the standby section 21 viathe conveyance path 31.

The inlet rollers 32 a and 32 b are arranged in the vicinity of thesheet supply port 31 p. The inlet rollers 32 a and 32 b convey the sheetS supplied to the sheet supply port 31 p to the exit rollers 33 a and 33b.

The exit rollers 33 a and 33 b are arranged in the vicinity of the sheetdischarge port 31 d. The exit rollers 33 a and 33 b receive the sheet Sconveyed by the inlet rollers 32 a and 32 b. The exit rollers 33 a and33 b convey the sheet S from the sheet discharge port 31 d to thestandby section 21.

The standby section 21 includes the standby tray (buffer tray) 211, aconveyance guide 212, discharge rollers 213 a and 213 b and an openingand closing driving section (not shown).

The back end part of the standby tray 211 is located in the vicinity ofthe exit rollers 33 a and 33 b. The standby tray 211 stacks a pluralityof the sheets S to enable them to stand by while the post processing iscarried out by the processing section 22.

FIG. 4 illustrates a relation between the standby tray 211, theprocessing tray 221 and the paddle section 25 described below. Thestandby tray 211 includes a first tray member 211 a and a second traymember 211 b. The first tray member 211 a and the second tray member 211b are driven by the opening and closing driving section. The first traymember 211 a and the second tray member 211 b move in a mutuallyapproaching direction and in a mutually separating direction in a sheetwidth direction W.

The first tray member 211 a and the second tray member 211 b support thesheet S conveyed from the exit rollers 33 a and 33 b in a state in whichthe first tray member 211 a and the second tray member 211 b approacheach other. On the other hand, the first tray member 211 a and thesecond tray member 211 b are separated in the mutually separatingdirection in the sheet width direction W so as to enable the sheet S tomove from the standby tray 211 towards the processing tray 221. In thisway, the sheet S supported by the standby tray 211 drops from a spacebetween the first tray member 211 a and the second tray member 211 btowards the processing tray 221.

An assist arm 41 shown in FIG. 3 is arranged above the standby tray 211.The sheet S discharged from the exit rollers 33 a and 33 b enters intothe space between the assist arm 41 and the standby tray 211.

The processing section 22 shown in FIG. 3 includes the processing tray221, a stapler 222, conveyance rollers 223 a and 223 b, and a conveyancebelt 224, a stopper 225 and a horizontal alignment section 51 (the firstalignment member 51 a and the second alignment member 51 b).

The processing tray 221 is arranged below the standby tray 211. Theprocessing tray 221 is inclined with respect to the horizontal directionin such a way as to gradually rise towards the downstream side of thesheet conveyance direction D. As for a plurality of sheets S moved tothe processing tray 221, the first alignment member 51 a and the secondalignment member 51 b align the deviation between the sheets S in thesheet width direction W.

The stapler 222 is arranged at an end part of the processing tray 221.The stapler 222 carries out a stapling (binding) processing on a bundleof the plurality of sheets S located on the processing tray 221.

The conveyance rollers 223 a and 223 b are arranged at a predeterminedinterval in the sheet conveyance direction D. The conveyance belt 224 isstretched over the conveyance rollers 223 a and 223 b. The conveyancebelt 224 is rotated in synchronization with the conveyance rollers 223 aand 223 b. The conveyance belt 224 conveys the sheet S between thestapler 222 and the discharge section 23.

The stopper 225 is arranged at the upstream side of the sheet conveyancedirection D as can be seen when viewed along the conveyance roller 223b. The stopper 225 is a member for receiving an end of the sheets Smoved from the standby tray 211 to the processing tray 221 to align themin the sheet conveyance direction D. In other words, the stopper 225 isa member serving as a sheet reference position when an alignmentprocessing in the sheet conveyance direction D is executed. The sheets Smoved towards the upstream side of the sheet conveyance directionthrough a first paddle 25 a and a second paddle 25 b described below arestruck against the stopper 225 to be aligned in the sheet conveyancedirection D. Hereinafter, aligning the sheets in the sheet conveyancedirection is referred to as a vertical alignment processing.

The horizontal alignment section 51 includes a pair of the firstalignment member 51 a and the second alignment member 51 b. The firstalignment member 51 a is located at the front side of the sheetpost-processing apparatus 2, and the second alignment member 51 b islocated at the rear side of the sheet post-processing apparatus 2. Thefirst alignment member 51 a and the second alignment member 51 b aremovable members in a sheet width direction W through the firsthorizontal alignment motor 29 a and the second horizontal alignmentmotor 29 b separately or independently. The horizontal alignment section51 can change the position of the sheet S by sliding the first alignmentmember 51 a and the second alignment member 51 b in the sheet widthdirection W. Thus, the first alignment member 51 a and the secondalignment member 51 b are also used at the time of sorting the sheet Sin the sheet width direction W.

The first alignment member 51 a and the second alignment member 51 b arearranged to have a predetermined space (interval). The processing tray221 loads the sheet S moved from the standby tray 211 in thepredetermined space. The first alignment member 51 a and the secondalignment member 51 b sandwich the sheets S and align edges of sheets Sin the sheet width direction W. Further, the first alignment member 51 aincludes a damper. The damper may be a spring type or may be formed witha member molded by a flexible material such as resin.

In FIG. 3, the paddle section 25 includes the first paddle 25 a, thesecond paddle 25 b, a rotational shaft 26 and a rotating member 27.

The rotational shaft 26 rotates around an axis of rotation. The axis ofrotation is a rotation center of the first paddle 25 a and the secondpaddle 25 b. The rotational shaft 26 is located below the standby tray211 and is fixedly mounted on the housing of the sheet post-processingapparatus 2. The rotational shaft 26 extends in the sheet widthdirection W. The rotational shaft 26 receives driving force from thepaddle motor 28 to rotate in an arrow A direction (in acounter-clockwise direction) in FIG. 3.

The first paddle 25 a and the second paddle 25 b are formed with anelastic material such as rubber or resin. The first paddle 25 aprotrudes in the diameter direction of the rotating member 27 to bemounted in the rotating member 27.

The first paddle 25 a has a length L1 in the diameter direction of therotating member 27.

The second paddle 25 b is arranged to have a predetermined angle withrespect to the first paddle 25 a. In other words, the second paddle 25 bis arranged a predetermined distance away from the rear of the firstpaddle 25 a in the rotation direction A in FIG. 3. The second paddle 25b protrudes in the diameter direction of the rotating member 27 to bemounted in the rotating member 27. The second paddle 25 b has a lengthL2 (<L1) in the diameter direction of the rotating member 27. The lengthL2 of the second paddle 25 b is shorter than the length L1 of the firstpaddle 25 a.

FIG. 5 is top view illustrating a relation between the paddle section 25and the processing tray 221.

A plurality of the paddle section 25 are attached the rotational shaft26 which extends in the sheet width direction W. Further the pluralityof the paddle section 25 is disposed on the rotational shaft 26symmetrically to the center of the processing tray 221. The plurality ofthe paddle section 25 is disposed on the rotational shaft 26 having apredetermined interval mutually in the sheet width direction.

The first paddle 25 and the second paddle 25 b are contacted with thesurface of the processing tray 221 when they rotate. The paddle section25 is rotated in synchronizing with rotation of the rotational shaft 26since the paddle section 25 is attached on the rotational shaft 26.

The horizontal alignment section 51 (the first alignment member 51 a andthe second alignment member 51 b) are positioned at “standby positions”,“first alignment positions” and “second alignment positions” in theprocessing tray 221. The horizontal alignment section 51 is movable byreceiving the driving force from the first horizontal alignment motor 29a and the second horizontal alignment motor 29 b.

“Standby positions” refer to positions at which the first alignmentmember 51 a and the second alignment member 51 b receive the sheetdischarged from the exit roller 33 a and 33 b or the sheet moved fromthe standby tray 211. The first alignment member 51 a and the secondalignment member 51 b are at the standby position in FIG. 5.

“First alignment position” refers to positions at which the firstalignment member 51 a and the second alignment member 51 b are shifted apredetermined distance from the center of the processing tray 221 in thesheet width direction W. In this position, the sheets are aligned in thesheet width direction W by the first alignment member 51 a and thesecond alignment member 51 b. Further an interval of distance existsbetween the first alignment member 51 a and the second alignment member51 b. The interval of distance is preset to be a distance equal orslightly shorter than the length of the sheet S serving as an alignedobject in the width direction of the sheet S. In FIG. 5, the firstalignment position is shown to be a position shifted toward to the areaof front side which has the stapler 222. Alternately, the firstalignment position may be a position shifted toward the rear side whichis opposite from the front side. The center of the processing tray 221refers to positions at which the value of X coordinate is “0” as shownin FIG. 5.

“Second alignment position” refers to positions at which the firstalignment member 51 a and the second alignment member 51 b align thesheets in the sheet width direction, on the basis of the center of theprocessing tray 221. In the second positions, an interval of distanceexists between the first alignment member 51 a and the second alignmentmember 51 b. The distance is preset to be a distance slightly wider thanthe length of the sheet S serving as an aligned object in the widthdirection W of the sheet S.

In FIG. 5, the value of “−X4”, “−X2”, “−X1”, “X2”, “X3”, and “X4” areshown in order to illustrate the positions of the first alignment member51 a and the second alignment member 51 b. Herein the value “0” is thecenter of the processing tray 221 and is a reference position.

Further table 1 illustrates the value of X coordinates which the firstalignment member 51 a and the second alignment member 51 b are locatedat each operation position. The value of X coordinates of the center ofthe processing tray 221 is “0”. “X1”, “X2”, “X3”, and “X4” have therelation that is “X1”<“X2”<“X3”<“X4”.

Specifically, when the horizontal alignment section 51 is located at thestandby positions, the first alignment member 51 a is located at “X4” inX coordinate and the second alignment member 51 b is located at “−X4” inX coordinate. The first alignment member 51 a and the second alignmentmember 51 b are located at symmetrically to the center of the processingtray 221.

When the horizontal alignment section 51 is located at the firstalignment positions, the first alignment member 51 a is located at “X3”in X coordinate and the second alignment member 51 b is located at “−X1”in X coordinate.

When the horizontal alignment section 51 is located at the secondalignment positions, the first alignment member 51 a is located at “X2”in X coordinate and the second alignment member 51 b is located at “−X2”in X coordinate. In the second alignment positions, the first alignmentmember 51 a and the second alignment member 51 b are located atsymmetrically to the center of the processing tray 221. Further theinterval between the first alignment member 51 a and the secondalignment member 51 b are narrower than the interval between them of atstandby position.

Next, a series of operations (the vertical alignment processing) of thefirst paddle 25 a and the second paddle 25 b are described withreference to FIG. 6 to FIG. 8.

FIG. 6 is a diagram illustrating home positions before the first paddle25 a and the second paddle 25 b are driven to rotate. The “homepositions” refer to positions at which the first paddle 25 a and thesecond paddle 25 b stand by when the sheet S is conveyed from the exitrollers 33 a and 33 b towards the standby tray 211 to be stacked or thesheet S is directly conveyed from the exit rollers 33 a and 33 b to theprocessing tray 221.

In FIG. 6, the first paddle 25 a is arranged at a position at which thefirst paddle 25 a does not protrude towards the downstream side of thesheet conveyance direction D with respect to the outer peripheralsurface of the exit roller 33 b can be seen when viewed from an axis 33c of the exit roller 33 b. From a different point of view, can be seenwhen viewed from the standby tray 211, the first paddle 25 a is locatedat the upstream side of the conveyance direction with respect to theouter peripheral surface of the exit roller 33 b located in the vicinityof the standby tray 211 and is arranged at a position at which theconveyance of the sheet S conveyed from the exit roller 33 b to thestandby tray 211 is not disturbed. The second paddle 25 b is arranged ata position at which the front end part is apart from the sheets S on theprocessing tray 221 at a predetermined distance.

The controller 24 drives a pair of the standby tray members 211 a and211 b in the mutually separating direction in the sheet width directionW to move the buffered sheets S to the processing tray 221, if thepredetermined number of sheets S is stacked on the standby tray 211.

The controller 24 drives the paddle motor 28 to rotate the rotationalshaft 26. The first paddle 25 a is rotated with the rotation of therotational shaft 26 and contacts with the sheet S dropped from thestandby tray 211. Then the first paddle 25 a forces the sheets S towardsthe processing tray 221.

FIG. 7 illustrates an operation of the vertical alignment processing tothe sheets S on the processing tray 221 by the first paddle 25 a throughthe further rotation of the first paddle 25 a in the arrow A direction(in the counter-clockwise direction).

The first paddle 25 a is further rotated in the arrow A direction toguide the sheet S onto the processing tray 221 from the state shown inFIG. 6. The first paddle 25 a contacts with the processing tray 221across the sheet S and then becomes a bent state. The first paddle 25 ais rotated in the arrow A direction to be kept in the bent state. Thefirst paddle 25 a moves the sheet S towards the stopper 225 located atthe upstream side of the sheet conveyance direction from the processingtray 221. In other words, the first paddle 25 a sandwiches a pluralityof the sheets S together with the processing tray 221. The first paddle25 a draws the sheets S into the stopper 225 to carry out the verticalalignment processing. Then the controller 24 controls rotation of therotational shaft 26 to suspend the first paddle 25 a and the secondpaddle 25 b after the first paddle 25 a separates from the sheets andbefore the second paddle 25 b contacts with the sheets.

FIG. 8 illustrates an operation of the vertical alignment processing tothe sheets S on the processing tray 221 by the second paddle 25 b. Thecontroller 24 controls the drive of the paddle motor 28. The controller24 controls the first paddle 25 a and the second paddle 25 b to rotatefrom the state in FIG. 7 to in the arrow A direction. The first paddle25 a and the second paddle 25 b are rotated by receiving the drive fromthe paddle motor 28. The second paddle 25 b performs the verticalalignment processing for the sheets again which previously performed thevertical alignment processing.

Then, the controller 24 controls the paddle motor 28 and positions thefirst paddle 25 a and the second paddle 25 b at the home positions (SeeFIG. 6).

The first paddle 25 a and the second paddle 25 b wait for that thefollowing sheets are received by the standby tray 211 in a state wherethey are located at the home positions. The above explanation is theseries of operation of the vertical alignment processing by the firstpaddle 25 a and the second paddle 25 b.

Next, the flow of the horizontal alignment processing and the verticalalignment processing for the sheets on the processing tray 221 by thehorizontal alignment section 51 (the first alignment member 51 a and thesecond alignment member 51 b) and the paddle section 25 is described.

FIG. 9 is a flowchart illustrating the vertical alignment processing andthe horizontal alignment processing executed by the horizontal alignmentsection 51 and the paddle section 25 under the control of the controller24.

The sheet S is discharged from the exit roller 33 a and 33 b to thestandby tray 211. The standby tray 211 buffers the plurality of sheets(for example three sheets) discharged from the exit roller 33 a and 33b. The controller 24 controls the first tray member 211 a and the secondtray member 211 b to be separated in the mutually separating directionin the sheet width direction W to enable the sheet S to move from thestandby tray 211 towards the processing tray 221 (ACT 101). Theplurality of sheets is dropped from the standby tray 211 to theprocessing tray 221. In FIG. 10, the first alignment member 51 a and thesecond alignment member 51 b wait for the plurality of sheets whichdropped from the standby tray 211 to the processing tray 221, at standbyposition on the processing tray 221.

The controller 24 controls the paddle section 25 to rotate. Thecontroller 24 performs the vertical alignment processing (See FIG. 7)for the plurality of sheets S by the first paddle 25 a (ACT 102). InFIG. 11, the sheets S are moved toward an upward of the conveyancedirection D by the first paddle 25 a.

In FIG. 12, the controller 24 moves the first alignment member 51 a andthe second alignment member 51 b from standby positions to the secondalignment positions and performs the horizontal alignment processing forthe sheets at the second alignment position (ACT 103). The plurality ofsheets which performed the vertical alignment processing in ACT 102 arealigned in the sheet width direction W at the second alignment position,by the first alignment member 51 a and the second alignment member 51 b.

In FIG. 13, the controller 24 performs the vertical alignment processing(See FIG. 8) for plurality of the sheets which aligned at the secondalignment position, by the second paddle 25 b (Act104). The firstalignment member 51 a and the second alignment member 51 b arepositioned at the second alignment positions at the time of the verticalalignment processing. Thus, the deviation between the sheets in thesheet width direction W can be suppressed.

In FIG. 14, the controller 24 moves the first alignment member 51 a fromthe second alignment position to the first alignment position (ACT 105).The second alignment member 51 b waits for a following process at thesecond alignment position.

In FIG. 15, the controller 24 moves the second alignment member 51 bfrom the second alignment position to the first alignment position (ACT106). The second alignment member 51 b can shift the sheets from thesecond alignment position to the first alignment position. Further thesecond alignment member 51 b can align the sheets with the firstalignment member 51 a in the sheet width direction W since the firstalignment member 51 a is located at the first alignment position. Inother words, the controller 24 performs the horizontal alignmentprocessing for sheets at the first alignment position by the firstalignment member 51 a and the second alignment member 51 b.

At the time, the controller 24 performs the horizontal alignmentprocessing for the sheets by abutting against the second alignmentmember 51 b which does not include a dumper mechanism. That is, sheetsare aligned at the end of the second alignment member 51 b side of thesheet as a reference.

The controller 24 determines whether a current performing sheet is alast sheet (Act 107). The controller 24 performs the processing of Act112, if the controller 24 determines the current performing sheet is notthe last sheet (NO in ACT 107).

In FIG. 16, the controller 24 moves the second alignment member 51 bfrom the first alignment position to the standby positions so as to loada following sheet S′ on the processing tray 221 (Act 112). The firstalignment member 51 a waits for a following process at the firstalignment position.

In FIG. 17, the controller 24 controls the exit rollers 33 a and 33 b toconvey the following sheet 5′ to the processing tray 221 (Act 113). Whenthe following sheet 5′ is conveyed to the processing tray 221, the firstalignment member 51 a is located at the first alignment position and thesecond alignment member 51 b is located at standby positions.

the controller 24 controls the paddle section 25 to rotate when thefollowing sheet 5′ is conveyed to the processing tray 221. Thecontroller 24 performs the vertical alignment processing for the sheet(See FIG. 7,8) by the first paddle 25 a and the second paddle 25 b (ACT114).

In FIG. 18, the following sheet 5′ is moved to the upward side in thesheet conveying direction D by above the vertical alignment processing.On the other hands, since the plurality of the sheets already aligned islocated at the first alignment position on the processing tray, theconveyance force against the plurality sheets applied by the paddlesection 25 becomes an uneven in the sheet width direction W. As theresult, the state of the plurality of the sheets already aligned becomesfailure (See FIG. 18).

In FIG. 19 illustrates that the states of the plurality of the sheetsalready aligned at the first alignment position becomes failure when thecontroller performs the processing of ACT 114.

The plurality of the sheets is aligned at the first alignment positionwhich is shifted to the other ends sides predetermined distance from thecenter of the processing tray 221. Thus, when the paddle section 25performs the vertical processing for sheets, the number of the paddlesection 25 which contact with the sheets on the processing tray 221becomes uneven in the sheet width direction W.

Specifically, in FIG. 19, in the area of left side with respect to thecenter line, the number of the paddle section 25 which contacts with thesheets is 2. The conveyance force F2 arise in the left area in FIG. 19and the sheet post-processing apparatus 2 performs the verticalalignment processing for the sheets at the force F2 in the area of leftside.

On the other hands, in the area of right side with respect to the centerline in FIG. 19, the number of the paddle section 25 which contacts withthe sheets is 1. The conveyance force F1 arises in the right area inFIG. 19. The sheet post-processing apparatus 2 performs the verticalalignment processing at the force F1 in the area of right side. Theforce F1 is less than the force F2 since a conveyance force applied byone paddle section is even.

Thus, the entire conveyance force applied by post-processing apparatus 2becomes uneven in the sheet width direction w. Thus, the states of theplurality of the sheets already aligned at the first alignment positionbecomes failure (as shown in FIG. 18) when the controller performs theprocessing of ACT 114.

In FIG. 20, the controller 24 move the second alignment member 51 b fromthe standby positions to the first alignment position (ACT 106) afterthe controller 24 performs processing ACT 114. At that time, the firstalignment member 51 a is located at the first alignment positons. Thus,the first alignment member 51 a can perform the horizontal alignmentprocessing by sandwiching the following sheet S′ and the plurality ofsheets positioned at the first alignment position with the secondalignment member 51 b.

The controller 24 determines whether a current sheet is last sheet again(ACT 107). The controller 24 performs the processing of ACT 108 if thecontroller 24 determines the current sheet is the last sheet (Yes in ACT107).

In FIG. 21, a deviation of the sheets might not be improved by onlyperforming the horizontal alignment processing in ACT 106. Therefore,the controller 24 moves the second alignment member 51 b from the firstalignment position to the second alignment position (ACT 108). The firstalignment member 51 a waits for a following process at first alignmentposition. It is not necessary to move the second alignment member 51 bto the second alignment position. The second alignment member 51 b maymove to a position wherein an interval between the first alignmentmember 51 a and the second alignment member 51 b is wider. For example,the certain position may be intermediate between the first alignmentposition and the second alignment position.

In FIG. 22, the controller 24 moves the second alignment member 51 bfrom the second alignment position to the first alignment position (ACT109). The second alignment member 51 a and the second alignment member51 b can perform the horizontal alignment processing at the firstalignment position by sandwich the sheets again.

As above, the sheet post-processing apparatus 2 performs a plurality ofthe horizontal alignment processing at the first alignment positionafter the vertical alignment processing by the paddle section 25 isperformed. Thus, the sheet post-processing apparatus 2 can improve thedeviation of the sheets on the processing tray 221 and discharge abundle of the sheet aligned to the discharge section.

The controller 24 controls the stapler 222 to perform the staplingprocessing for the plurality of sheets aligned at the first alignmentposition by driving the stapler 222 (ACT 110).

The controller 24 controls the conveyance rollers 223 a and 223 b todischarge the sheets stapled to the movable tray 23 b (ACT 111). Aseries of processing is finished.

According to the embodiment, the sheet post-processing apparatus 2performs a plurality of the horizontal alignment processing at the firstalignment position after the vertical alignment processing by the paddlesection 25 is performed. Thus, the sheet post-processing apparatus 2 canimprove the deviation of the sheets on the processing tray 221 anddischarge a bundle of the sheet aligned to the discharge section.

Further, the sheet post-processing apparatus 2 performs the horizontalalignment processing in advance in ACT 103 before the sheetpost-processing apparatus 2 performs the horizontal alignment processingfor the sheets in ACT 106 and ACT 109. Thus, the sheet post-processingapparatus 2 can shift the plurality of the sheets aligned to the otherend side on the processing tray 221. Accordingly, in ACT 114, when thesheet post-processing apparatus 2 performs the vertical alignmentprocessing for the sheet, the sheet post-processing apparatus 2 canprevent the deviation of the sheets from occurring.

The Second Embodiment

In the second embodiment, the sheet post-processing apparatus 2 changesthe number of the horizontal alignment processing for the sheets whichperformed the vertical alignment processing at the first alignmentposition, based on the number of sheet to be supposed to process.

FIG. 23 is a flowchart illustrating the processing performed by thecontroller 24.

Since the processing of ACT 201 to ACT 207 is common to firstembodiment, the illustration regarding these processing is omitted. Theprocessing of ACT 208 and subsequent processing is illustrated below.

The controller 24 determines whether a current sheet is the last sheet(ACT 207). The controller 24 determines whether the number of the sheetswhich is to be processed is greater than the predetermined the number ofthe sheets (ACT 208), if the controller 24 determines the current sheetis the last sheet (Yes in ACT 207). The reason which is determiningwhether the number of the sheets which is to be processed is greaterthan the predetermined the number of the sheets is recited below.

In a case that more the number of the sheets increase, more thickness ofthe sheets on the processing tray 221 grows in thickness. Accordingly,an area of contact between the paddle section 25 and the sheetsincreases when the paddle section 25 performs the vertical alignmentprocessing for the sheets on the processing tray 221. Increasing thearea of contact encourages the unevenness of the conveyance force by thepaddle section 25 at the first alignment position. Thus, if the more thenumber of the sheets which is to be processed increase, the more thedeviation of the sheet at the first alignment position is bigger afterthe vertical alignment processing at the first alignment position.

If the controller 24 determines the number of the sheets which is to beprocessed is greater than the predetermined the number of the sheets(Yes in ACT 208), the controller 24 performs the horizontal alignmentprocessing for the plurality of the sheets at first alignment positionagain by performing the processing of ACT 209 and ACT 210. And then thecontroller 24 performs the processing of ACT 211 and ACT 212.

On the other hand, the controller 24 determines the number of the sheetswhich is to be processed is less than the predetermined the number ofthe sheets (No in ACT 208), the controller 24 performs the processing ofACT 211 and ACT 212 without performing the processing of ACT 209 and ACT210.

In this way, the sheet post-processing apparatus can change the how toalignment processing at the first alignment position and improve theprocessing speed by performed by post-processing apparatus, based on thenumber of sheet to be supposed to process.

Third Embodiment

The processing performed by the controller 24 is illustrated.Specifically, the controller 24 determines whether a printing job sentfrom the image forming apparatus 1 has information which is indicationof the performing the stapling processing. And then the controller 24changes the number of the horizontal alignment processing for the sheetswhich performed the vertical alignment processing at the first alignmentposition.

FIG. 24 is a flowchart illustrating the processing performed by thecontroller 24.

Since the processing of ACT 301 to ACT 307 is common to firstembodiment, the illustration regarding these processing is omitted. Theprocessing of ACT 308 and subsequent processing is illustrated below.The controller 24 determines whether a current sheet is the last sheet(ACT 307). If the controller 24 determines the current sheet is the lastsheet (ACT 307), the controller 24 determines whether the job hasinformation regarding performing a staple processing, wherein the job issent from the image information apparatus 1 (ACT 308). The reason whythe controller 24 determines whether the job has information regardingperforming a staple processing is described as follows. When the sheetpost-processing apparatus 2 performs the stapling process, it isnecessary to be the state of the sheets aligned is better than when thesheet post-processing apparatus does not performs the staplingprocessing.

The controller 24 determines the printing job has information regardingperforming a staple processing (Yes in ACT 308), the controller 24performs the horizontal alignment processing for sheets on theprocessing tray 221 by performing the processing of ACT 309 and ACT 310.Thereafter, the controller 24 performs the processing of ACT 311 and ACT312 and finishes the series of the processing.

On the other hands, the controller 24 determines the printing job doesnot have information regarding performing a staple processing (No in ACT308), the controller 24 controls the discharge section to discharge thesheets to a movable tray 23 b without performing the processing of ACT309 to ACT 311. The controller 24 finishes the series of the processing.

In this way, the sheet post-processing apparatus can performs thestapling processing for the sheets aligned desirably at the firstalignment portions.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the inventions. Indeed, the novel embodiments described hereinmay be embodied in a variety of other forms; furthermore, variousomissions, substitutions and changes in the form of the embodimentsdescribed herein may be made without departing from the spirit of theinventions. The accompanying claims and their equivalents are intendedto cover such forms or modifications as would fall within the scope andspirit of the inventions.

What is claimed is:
 1. An image forming apparatus, comprising: a printerconfigured to form images on a sheet; a sheet conveying sectionconfigured to convey the sheet output from the printer a processing trayconfigured to receive the sheet from the sheet conveying section; avertical alignment section configured to align the sheet on theprocessing tray in a sheet conveying direction by rotation of thevertical alignment section; a horizontal alignment section configured toalign the sheet, in a sheet width direction orthogonal to the sheetconveying direction, between a first alignment member and a secondalignment member; and a controller configured to control: the horizontalalignment section to shift the sheet to a first alignment position thatis a predetermined distance from the center of the processing tray inthe sheet width direction, the horizontal alignment section to align thesheet in the sheet width direction at the first alignment position, andthe vertical alignment section to align the sheet in the conveyingdirection at the first alignment position.
 2. The apparatus according toclaim 1, wherein the sheet conveying section comprises conveying roller.3. The apparatus according to claim 1, wherein the controller is furtherconfigured to: determine whether the sheet conveyed to the processingtray is a last sheet output from the printer in a print job, control thesheet conveying section to convey a next sheet after the sheet to theprocessing tray when the sheet is not the last sheet, and control thehorizontal alignment section to realign the sheet at the first alignmentposition when the sheet conveyed to the processing tray is not the lastsheet.
 4. The apparatus according to claim 1, further comprising adischarge tray, wherein the controller is further configured to:determine whether a number of sheets on the processing tray is apredetermined number, control the horizontal alignment section torealign the sheet at the first alignment position when the controllerdetermines the number of sheets is the predetermined number, control theconveying section to discharge the sheet to the discharge tray when thenumber of sheets on the processing tray is not predetermined number. 5.The apparatus according to claim 1, further comprising: a dischargetray; and a stapler configured to staple sheets on the processing tray,wherein the controller is further configured to: determine whether aprinting job includes instructions for stapling of sheets associatedwith the print job, control the horizontal alignment section to alignthe sheet at the first alignment position the printing job includesinstructions to staple sheets associated with the printing job, andcontrol the conveying section to discharge the sheet to the dischargetray and when the printing job does not include instructions to staplesheets associated with the printing job.
 6. The apparatus according toclaim 1, wherein the controller is configured to control the horizontalalignment section to align the sheet in the sheet width direction at asecond alignment position, which is different from the first alignmentposition, before shifting the sheet to the first alignment position. 7.A method for controlling an image formation process of an image formingapparatus, the method comprising: forming images on a sheet with aprinter; conveying the sheet output from the printer with a sheetconveying section to a processing tray; receiving the sheet from thesheet conveying section at the processing tray; aligning the sheet onthe processing tray in a sheet conveying direction using rotation of avertical alignment section; aligning the sheet on the processing tray,in a sheet width direction orthogonal to the sheet conveying direction,between a first alignment member and a second alignment member using ahorizontal alignment section; and shifting the sheet to a firstalignment position that is a predetermined distance from the center ofthe processing tray in the sheet width direction using the firstalignment member and the second alignment member, wherein the firstalignment position is a predetermined distance from the center of theprocessing tray in the sheet width direction.
 8. The method according toclaim 7, wherein the sheet conveying section comprises rollers.
 9. Themethod according to claim 7, further comprising: determining whether thesheet conveyed to the processing tray is a last sheet in a printing job;conveying a next sheet after the sheet to the processing tray with theconveying section the sheet conveyed to the processing tray is not thelast sheet in the printing job; and aligning the sheet at the firstalignment position when the sheet conveyed to the processing tray is thelast sheet in the printing job.
 10. The method according to claim 7,further comprising: receiving the sheet discharged from the processingtray at a discharge tray; determining whether a number of sheets on theprocessing tray is a predetermined number; aligning the sheet at thefirst alignment position using the horizontal alignment section when thenumber of sheets on the processing tray is the predetermined number; anddischarging the sheet to the discharge tray when the number of sheetswhich on the processing tray is not the predetermined number.
 11. Themethod according to claim 7, further comprising: receiving a sheetdischarged from the processing tray at a discharge tray; receiving aprinting job sent including instructions for stapling sheets associatedwith the printing job; aligning the sheet at the first alignmentposition using the horizontal alignment section when the printing jobincludes instructions to staple sheets associated with the printing job;and discharging the sheet to the discharge tray when the printing jobdoes not include instructions to staple sheets associated with theprinting job.
 12. The method according to claim 7, further comprising:aligning the sheet in the sheet width direction at a second alignmentposition different from the first alignment position before shifting thesheet to the first alignment position.